Methods of using vvectors comprising nucleic acid and nucleic acid variants encoding FVIII protein are disclosed. In particular embodiments, a method of treating a human having hemophilia A includes administering a recombinant adeno-associated virus (rAAV) vector comprising a nucleic acid encoding Factor VIII (FVIII) or nucleic acid variant encoding Factor VIII (FVIII) having a B domain deletion (hFVIII-BDD). In some aspects, a nucleic acid variant has 95% or greater identity to SEQ ID NO:7 and/or a nucleic acid variant has no more than 2 cytosine-guanine dinucleotides (CpGs). In other aspects, a rAAV vector is administered to the human at a dose of less than about 6x1012 vector genomes per kilogram (vg/kg).
